Piston pumps



Feb. 28, 1967 w UN L R ETAL 3,306,211

PISTON PUMPS Filed May 4, 1964 4 Sheets-Sheet 1 Feb. 28, 1967 w KUNZLER EI'AL 3,306,211

PISTON PUMPS Filed May 4, 1964 4 Sheets-Sheet z 5 Fig.2

Feb. 28, 1967 w. KUNZLER ETAL 3,306,211

PISTON PUMPS Filed May 4, 1964 4 Sheets-Sheet 5 United States Patent Ofl ice 3,396,211 Patented Feb. 28, I967 3,306,211 PHSTON PUMPS Werner Kunzler, Munich, and Karl Knauer, Gauting,

near Munich, Germany, assignors to Munchner Motorzubehor G.m.b.H., Munich, Germany, a corporation of Germany Fiied May 4, 1954, Ser. No. 364,638

Claims priority, application Germany, Mar. 16, 1964,

9 Claims. (Cl. 10337) This invention relates to piston pumps and has reference particularly to liquid supply pumps of the kind each comprising a pump housing which has mounted therein a rotary drive shaft having a drive cam, at least one pump body provided on the pump housing and extending radially with respect to the axis of the drive shaft said pump body being provided with an operating chamber, a drive piston mounted in the pump body and arranged to be reciprocated by the drive cam, and a supply piston projecting into the operating chamber and mounted for reciprocation in the pump body and arranged to cooperate and move with the drive piston. Usually, there are a plurality of pump bodies arranged in star formation around the pump housing.

Moreover, the present invention is concerned with a device for regulating the quantity of flow in a piston pump of the kind concerned.

In piston pumps of this kind, the regulation of the quantity of flow is, in most cases, performed in such a way that the effective supply stroke of the supply piston is varied by a mechanical regulating device which is, for example, operated by turning the piston with a control edge, or which is interposed between the drive cam and the piston. Such regulating devices, however, require complicated and thus expensive constructions and are, moreover, operable only by using very high actuating forces.

The object of the invention is to provide a device for regulating the quantity of flow which can be produced with a maximum economy of constructional parts and requires a minimum actuating force to operate it. In accordance with the invention, the pump is provided with a suction conduit which is connected to said operating chamber and through which fluid at a low pressure and acting on the supply piston, is supplied to said chamber, and a device for regulating the quantity of flow which comprises an adjustable throttle arranged in the suction conduit for regulating the low pressure of the fluid supplied to the operating chamber, the drive piston and the supply piston defining between them a chamber in which prevails a constant pressure independent of the variable low pressure of the fluid supplied to the operating chamber.

Specific examples of the invention embodying the foregoing and other features will now be described in detail with reference to the accompanying drawings.

In these drawings:

FIGURE 1 is a longitudinal section through the pump of one example, showing one pump body at the end of the supply stroke,

FIGURE 2 is a cross section through the pump of FIGURE 1, showing the pump concerned at the end of the suction stroke,

FIGURE 3 is a longitudinal section through the pump of another example,

FIGURE 4 is a cross sectional view showing the throttle of the pump illustrated in FIGURE 3, and

FIGURE 5 shows a throttle of a different construction.

In FIGURE 1 there is shown a pump housing 1 which is preferably of cylindrical shape and has rotatably mounted therein a drive shaft 2 having an eccentric drive cam 2a. Ball-bearings 3 and 4 are interposed between the pump housing and the drive shaft.

A plurality of pump bodies 5, arranged in star formation, i.e. so as to extend radially with respect to the axis of the drive shaft 2, are mounted upon the periphery of the pump housing 1. In the present example there are three such pump bodies, and these are fixedly secured to the pump housing 1 by several screws (not shown). The end face of each pump body 5 is seated in a recess 1a in the pump housing 1. Accommodate in each pump body 5 is a valve unit 6 having a T-shaped suction valve on and a compression valve 6b, also of T-shape. In addition, a piston sleeve 7 is mounted in each pump body and receives a drive piston 8. The valve units 6 and the piston sleeves 7 are fixed in the pump bodies 5 by nuts 9. A return spring 10 is inserted between each nut 9 and the drive piston 8 is concerned. Introduced into each piston sleeve 7 above the drive piston 8 is a stepped supply piston 11 having a recess 11a which surrounds the reduced end 8a of the drive piston 8. Inserted into the recess 11a is a small plate 11b, which is made of a synthetic material, e.g. polyamide, for dampening striking together of the pistons 8 and 11. Located in the piston sleeve 7' is a spring ring 12; the spring 13 of the suction valve 6:: presses against one side of this ring 12 and a loading spring 14, which is Weaker than the return spring 10 and bears against the shoulder of the stepped supply piston 11, presses against the other side.

A central collecting chamber Is surrounding the drive shaft 2. is formed in the pump housing 1 and is sealed off from the outside of the pump by means of a sealing ring 1b bearing against the drive shaft.

The collecting chamber is is connected through a connection is" and, if desired, through a valve 1rd to a liquid supply container 19, so that the leaking liquid which collects in the chamber is, can flow back into the container. Thus, the arrangement is such that a constant pressure always prevails in the collecting chamber is.

Each pump unit 5 has a suction duct 5s which is separated from the central collecting chamber Is by a plug 5s. Secured in each pump body 5 is a connecting nipple 26 which projects into the suction ducts 5s and to which a suction pipe 20s can be connected. A connecting suction pipe 26's.? joins together the suction pipes Zlis of the three pump bodies, and, in turn, is connected through a variable throttle 18 to the liquid container 19 which is at an elevated location, so that the liquid flows under gravity into the pipes 205', Zllss.

A central compression chamber id in the form of an internally screw-threaded counter-sunk bore is also provided in the pump housing 1, co-axial with the collecting chamber 15'. Moreover, a compression duct 5d, provided in each pump body, is connected, through a connecting conduit id in the housing 1, with the central compression chamber Id. In the illustrated example, therefore, three compression conduits 1d open into the central compression chamber 1d. The compression chamber is provided with a connecting nipple 1d" of known type (and therefore not shown in detail), the connecting conduit ld' thereof being adapted to be connected to the utility point (not shown).

To seal the conduit system between each pump body 5 and the pump housing 1, a sealing ring of copper or the like is inserted in a recess between the parts 1 and 5 at each joint between the connecting conduits 1d and 5d, this ring being compressed in sealing fashion when the pump body concerned is tightened down on the pump housing. A groove 16 is formed in the end face of each pump body concentric with the corresponding supply piston, and a rubber sealing ring 17 is disposed in this groove.

The throttle 18 which is inserted in the suction pipe Ztlss, is adjustable by means of a hand lever 18a to give varying cross sectional areas of flow. Each setting can, for example, be read off a scale 18s associated with the hand lever 18a. The quantity of liquid flowing from the liquid container 19 into the pipes 20s is, therefore, controlled by the throttle 18 so that a low pressure which is variable within specific limits, prevails in the suction ducts 5s of the pump bodies 5.

A chamber 21 inside the piston sleeve 7 between the drive piston 8 and the supply piston 11 is permanently connected by a number of conduits, 8b, 8c, 8d, inside the drive piston 8 to the central collecting chamber Is in the pump housing 1. Accordingly, the constant pressure of the chamber 1s prevails in the chamber 21.

FIGURE 1 shows the pump with the pump 'body which is seen in this figure, at the end of the compression or supply stroke, Now, if the drive cam 2a is turned, e.g. in the clockwise direction, the drive piston 8 is moved downwardly under the action of its return spring 10. The loading spring 14 strives to move the supply piston 11 downwardly and to maintain the positive engagement between the pistons 8 and 11. During this initial downwards movement of the supply piston 11, the suction valve 6a opens and comes to bear against the end face of the piston sleeve 7. The liquid now flows out of the suction duct 5s through several countersinks 61m in the periphery of the suction valve 6a through the valve body 6 and into the operating chamber 22. The downwards movement of the supply piston 11 which moves with drive piston, however, takes place only until the unloading force of the loading spring is the same as the difference between the low pressure inside the operating chamber 22 and the constant pressure in the collecting chamber 1s and hence in the chamber 21. Then the supply piston 11 comes to rest, e.g. at a position half way along its complete stroke, whilst the drive piston 8 moves further downwards.

As soon as the drive piston 8 has terminated its return movement and is again moved upwards under the impulsion of the liquid from the chamber 21,- at a specific moment of time it again comes into engagement with the stationary supply piston 11 and moves this with it, so that the actual effective supply stroke of the supply piston 11 now begins. The suction valve 6a is closed and the supply liquid flows through its axial conduit to the compression valve 611 and then into the conduit ld to the utility point.

By selectively regulating the low pressure in the suction chamber 22 relatively to the constant pressure in the chamber 21, in accordance with the present invention, the effective suction stroke of the supply piston 11 is adjusted in a simple manner, the drive piston 8 having a constant stroke; if there is the same pressure in the suction chamber 22 as in the chamber 21, the suction stroke of the supply piston 11 is the same as the stroke of the drive piston 8 (maximum supply quantity). On the other hand, if the low pressure in the chamber 22 is made smaller than the pressure in the chamber 21 by the throttle 18, the suction stroke of the supply piston is made correspondingly smaller than the stroke of the drive piston 8. This allows the suction stroke of the supply piston 11 to be made only a fraction of the stroke of the drive piston 8 (minimum supply quantity).

Only very small actuating forces are required to control and move the hand lever 18a. The throttle can be any desired commercial liquid valve which can be easily connected into the pipe 20ss. Instead of providing a handoperated regulating device directly on the pump, the throttle 18 may be arranged at a position remote from the pump, this advantageously providing a remote control.

The examples illustrated in FIGURES 3 to 5 have for their object to provide a further development of the regulating device described above in connection with FIG- URES 1 and 2, by simplifying and shortening the connections between the variable throttle and the pump.

Referring to FIGURE 3, the individual pump bodies 5 with their components are arranged in star formation on the pump housing 1 radially with respect to the drive shaft 2 in the same way as described with reference to FIGURES 1 and 2. The same parts are given the same reference numerals as in FIGURES 1 and 2. Accordingly, it is considered unnecessary to describe the component parts again.

In contrast to the example of FIGURES 1 and 2, in this case a flange 22 is secured by means of several screws 26 to the end face of the pump housing 1 in which is formed the compression chamber 1d. Mounted in a stepped transverse bore 20ss in this flange is a throttle in the form of a hollow rotary valve 18 having a control edge 18b, this throttle being secured against axial movement by means of a nut 23. Fixed to the projecting end of the rotary valve 18 is a handle 24 having a knob 25. The transverse bore 20ss is connected through a perpendicularly extending bore 205 to an annular collecting chamber 22a at the bearing face of the flange 22. A collecting compression chamber 29 is arranged concentrically with the annular chamber 22a, two sealing rings 27 and 28 sealing off the chambers from one another and from the outside of the pump.

Each suction duct 5s of the pump bodies 5 is in communication through conduits 1e and 1 in the pump housing 1 with the annular chamber 22a. However, the collecting chamber 1s with a constant pressure which is independent of the variable low pressure in the suction side, can, if necessary, be connected through the valve lsd illustrated in FIGURE 1, to the liquid supply contanier (not shown).

The flange 22 is provided externally with a connecting nipple 19a for the suction pipe which leads to the supply container (not shown) and which is connected through the conduit 20, the control edge 18b of the throttle 18 and the bores 205s, 20s, to the annular chamber 22a. In addition, the flange 22 has an external connecting nipple 1d for the compression pipe leading to the utility point. This nipple is connected through a transverse conduit 22b to the compression chambers 29 and 1a.

In this case, the collecting chamber Is is connected through transverse conduits 7a and 7b, which are machined in the piston sleeve 7 at different heights, to the chamber 21 between the drive piston 8 and the supply piston 11, the constant pressure which is independent of the variable low pressure in the suction side, prevailing in this chamber 21.

By actuating the hand lever 25 the rotary valve 18 with its control edge 18b is turned and the low pressure at the suction side of the pump is thereby controlled (as described in connection with FIGURES 1 and 2). In this way, the piston parts assume a specific relative position during the supply stroke, and the quantities supplied are correspondingly regulated.

As shown in FIGURE 5, the throttle for regulating the suction pressure can be operated not only by hand but also automatically by the supply pressure. In this case, the

throttle is in the form of a sliding member 30 having a control edge 30a and is movable against the action of a spring 31 in the transverse conduit ss in the flange 22. A valve seat b of the sliding member 30, which is secured against turning movement by guide means (not shown), thus forms a conduit 32a for a closure plug 32 which is secured, e.g. screwed, in the flange 22 and is sealed off from the outside by a sealing ring 33. The compression chamber 29 and 1d is connected through a transverse conduit 29' in the flange 22 to the conduit 32a so that the high pressure in the supply chamber 29 and 1d acts on the sliding member 30. The spring 31 which is either replaceable and/ or adjustable, is of such a strength that, when a specific desired high pressure is attained in the supply line, the sliding member 30 moves against the action of the spring 31 and, by its control edge 30a, throttles or completely shuts olf the flow from the conduit 20a to the suction side of the pump. Thus, the low pressure in the suction side is correspondingly controlled. By a suitable selection of the lengths of the sealed parts of the sliding member 30 and the arrangement of the control edge 30a, an automatic control, dependent of the supply pressure, of the low pressure in the suction side of the pump can be produced within a wide range.

We claim:

1. A piston pump which includes, in combination, a pump housing; a rotary drive shaft mounted in said housing; a drive cam provided on said drive shaft; at least one pump body provided on the pump housing and extending radially with respect to the axis of the drive shaft, said pump body being provided with an operating chamber; a drive piston mounted in the pump body and arranged to be reciprocated in the body by the drive cam on the drive shaft, a supply piston mounted for reciprocation in the pump body and arranged to co-operate and move with the drive piston, said supply piston projecting into the aforesaid operating chamber; a suction conduit which is connected to said operating chamber and through which fluid at a low pressure and acting on the supply piston, is supplied to said chamber; and a device for regulating the quantity of flow which comprises an adjustable throttle arranged in the suction conduit for regulating the low pressure of the fluid supplied to the operating chamber, the drive piston and the supply piston defining between them a chamber in which prevails a constant pressure independent of the variable low pressure of the fluid supplied to the operating chamber.

2. A piston pum as claimed in claim 1, in which an insert, made of a synthetic material, is introduced between the co-operating parts of the drive piston and the supply piston, this insert dampening striking together of the pistons.

3. A piston pump as claimed in claim 1, in which, to provide for remote control of the flow regulation of the pump, the throttle is arranged in the suction conduit at a location remote from the pump.

4. A piston pump which includes, in combination, a pump housing; a rotary drive shaft mounted in said housing; a drive cam provided on said drive shaft; at least one pump body provided on the pump housing and extending radially with respect to the axis of the drive shaft, said pump body being provided with an operating chamber; a drive piston mounted in the pump body and arranged to be reciprocated in the body by the drive cam on the drive shaft, a supply piston mounted for reciprocation in the pump body and arranged to cooperate and move with the drive piston, said supply piston projecting into the aforesaid, operating chamber; a flange secured to the pump housing and provided with a suction conduit which is connected through a collecting chamber and suction ducts in the pump housing and the pump body to said operating chamber, fluid at a low pressure and acting on the supply piston, being supplied through this suction conduit to the operating chamber; and a device for regulating the quantity of flow which comprises an adjustable throttle disposed in the suction conduit in the flange for regulating the low pressure of the fluid supplied to the operating chamber, the drive piston and the supply piston defining between them a chamber in which prevails a constant pressure independent of the variable low pressure of the fluid supplied to the operating chamber.

5. A piston pump as claimed in claim 4, including a rotary valve which constitutes the adjustable throttle in the flange, and a handle connected to this valve and projecting from the flange for adjusting the valve.

6. A piston pump as claimed in claim 4, including a sliding member which constitutes the adjustable throttle, and a loading spring which is associated with the sliding member and against the action of which the latter is movable in the flange to regulate the low pressure of the fluid supplied to the operating chamber.

7. A piston pump which includes, in combination, a pump housing provided with a compression chamber into which flows fluid under a high pressure pumped by the pump; a rotary drive shaft mounted in said housing; a drive cam provided on said drive shaft; at least one pump body provided on the pump housing and extending radially with respect to the axis of the drive shaft, said pump body being provided with an operating chamber; a drive piston mounted in the pump body and arranged to be reciprocated in the body by the drive cam on the drive shaft; a supply piston mounted for reciprocation in the pump body and arranged to cooperate and move with the drive piston, said supply piston projecting into the aforesaid operating chamber; a flange secured to the pump housing and provided with a suction conduit which is connected through a collecting chamber and suction ducts in the pump housing and the pump body to said operating chamber, fluid at a low pressure and acting on the supply piston, being supplied through this suction conduit to the operating chamber; and a device for regulating the quantity of flow which comprises an adjustable throttle in the form of a sliding valve member disposed in the suction conduit for regulating the low pressure of the fluid supplied to the operating chamber, said valve member having associated therewith a control chamber; and a loading spring which is associated with the valve member and against the action of which the latter is movable to vary the quantity of flow, the said control chamber being connected to the aforesaid compression chamber so that the high pressure of the fluid in the compression chamber acts on the sliding valve member, the drive piston and the supply piston defining between them a chamber in which prevails a constant pressure independent of the variable low pressure of the fluid supplied to the operating chamber.

8. A piston pump as claimed in claim 7, in which the flange is provided, at its periphery, with threaded bores which receive connecting nipples for compression and suction pipes to be connected to the pump.

9. A piston pump which includes, in combination, a pump housing provided with a central collecting chamber; a rotary drive shaft mounted in said housing; a drive cam provided on said drive shaft; at least one pump body provided on the pump housing and extending radially with respect to the axis of the drive shaft, said pump body being provided with an operating chamber; a piston sleeve mounted in said pump body and provided with conduits at different positions along its length which are connected to the said central collecting chamber; a drive piston mounted in the piston sleeve and arranged to be reciprocated in the piston sleeve by the drive cam on the drive shaft; a supply piston projecting into the aforesaid operating chamber and mounted for reciprocation in the piston sleeve and arranged to co-operate and move with the drive piston; a suction conduit which is connected to said operating chamber and through which fluid at a low pressure and acting on the supply piston, is supplied to said chamber; and a device for regulating the quantity of flow which comprises an adjustable throttle arranged in the suction conduit for regulating the low pressure of the fluid supplied to the operating chamber, the drive piston and the supply piston defining between them a chamber which is connected to said conduits in the piston sleeve and hence to the central collecting chamber and in which prevails a constant pressure independent of the variable low pressure of the fluid supplied to the operating chamber.

References Cited by the Examiner UNITED STATES PATENTS 8 Deschamps 103-40 Huber 10340 Livers 103--40 Gratzmuller 103-40 Van Gerpen 103--38 Van Gerpen 103-38 Bauerlein 103-40 Kress 103-174 Raymond 103-38 Heintzrnann 103-67 LAURENCE V. EFNER, Primary Examiner. 

1. A PISTON PUMP WHICH INCLUDES, IN COMBINATION, A PUMP HOUSING; A ROTARY DRIVE SHAFT MOUNTED IN SAID HOUSING; A DRIVE CAM PROVIDED ON SAID DRIVE SHAFT; AT LEAST ONE PUMP BODY PROVIDED ON THE PUMP HOUSING AND EXTENDING RADIALLY WITH RESPECT TO THE AXIS OF THE DRIVE SHAFT, SAID PUMP BODY BEING PROVIDED WITH AN OPERATING CHAMBER; A DRIVE PISTON MOUNTED IN THE PUMP BODY AND ARRANGED TO BE RECIPROCATED IN THE BODY BY THE DRIVE CAM ON THE DRIVE SHAFT, A SUPPLY PISTON MOUNTED FOR RECIPROCATION IN THE PUMP BODY AND ARRANGED TO CO-OPERATE AND MOVE WITH THE DRIVE PISTON, SAID SUPPLY PISTON PROJECTING INTO THE AFORESAID OPERATING CHAMBER; A SUCTION CONDUIT WHICH IS CONNECTED TO SAID OPERATING CHAMBER AND THROUGH WHICH FLUID AT A LOW PRESSURE AND ACTING ON THE SUPPLY PISTON, IS SUPPLIED TO SAID CHAMBER; AND A DEVICE FOR REGULATING THE QUANTITY OF FLOW WHICH COMPRISES AN ADJUSTABLE THROTTLE ARRANGED IN THE SUCTION CONDUIT FOR REGULATING THE LOW PRESSURE OF THE FLUID SUPPLIED TO THE OPERATING CHAMBER, THE DRIVE PISTON AND THE SUPPLY PISTON DEFINING BETWEEN THEM A CHAMBER IN WHICH PREVAILS A CONSTANT PRESSURE INDEPENDENT OF THE VARIABLE LOW PRESSURE OF THE FLUID SUPPLIED TO THE OPERATING CHAMBER. 